The present invention relates to a matrix infrared detector comprising a matrix of infrared elements, particularly for a camera, for example for aerial reconnaissance.
The advantage of such matrix detectors lies in the fact that the elements of the matrix are addressed, or scanned, electronically, and no longer mechanically by luminous spot.
Addressing consists, in fact, with the aid of electronic processing means, either in integrating the signals delivered by the elements of the matrix, or in sequentially switching the elements of the matrix on a circuit for reading the signals delivered. It will therefore be appreciated that each of the elements of the matrix is connected to these electronic processing means.
It has already been proposed to couple the elements of the matrix to electronic circuits for processing by lines. However, this solution presents drawbacks due to the length of the connecting lines, in which parasitic noises are generated, and to their number which provokes a heat load due to the line losses. Furthermore, this solution leads to detection modules of considerable dimensions, with a large number of elementary welds.
It was then proposed to manufacture a matrix infrared detector by taking a first semiconductor wafer of one of two types p and n, previously cut out, by diffusing zones of the other of the two types, from the front face of the wafer to be illuminated, to define junctions and to form a matrix of elementary detectors, by disposing the first detection wafer on a second semiconductor wafer adapted to process the signals delivered by the elementary detectors of the matrix of the first wafer, and by forming, on the front face of the detection wafer, on one of the walls thereof connecting its front face and the face of the second processing wafer facing the detection wafer, and on this face of the processing wafer, metallic contact terminals connecting said zones of the detection wafer to associated metallization zones of the processing wafer.
Such a process of manufacture already presents the advantage of being able to form the connecting terminals collectively in one operation.
However, this process presents the drawback whereby, before these connecting terminals are made, the two detection and processing wafers must already be one on the other. This results in a risk of misalignment of the connecting terminals and the metallization zones of the processing wafer. There is also a risk of electrical discontinuity due to the structural discontinuity at the joint between the two wafers, generally constituted by adhesive.